Moving picture coding apparatus, moving picture decoding apparatus, and stream data

ABSTRACT

A signal separation unit (101) separates an input picture made up of component pictures of RGB, each of which has an equal number of pixels as the input picture, into three component pictures, and outputs the three component pictures. Each of coding units (102 to 104) codes one of the component pictures into an intra-picture prediction coded picture or an inter-picture prediction coded picture, and outputs a bit stream corresponding to the component picture. A bit stream multiplexing unit (105) multiplexes three bit streams outputted from the three coding units into one bit stream, and outputs the bit stream. Each of the coding units (102), (103) and (104) determines a prediction method for the component picture at the time of coding.

This application is a divisional of Application Ser. No. 11/996,034, nowU.S. Pat. No. 8,204,113, which is the National Stage of InternationalApplication Ser. No. PCT/JP2006/314184, filed Jul. 18, 2006.

TECHNICAL FIELD

The present invention relates to a moving picture coding apparatus, amoving picture decoding apparatus, and stream data, when coding ordecoding a picture made up of N component pictures (N is an integer thatis two or greater), each of the component pictures having equal numberof pixels.

BACKGROUND ART

In a Moving Picture Experts Group 4 Advanced Video Coding (MPEG-4 AVC)standard (Non-patent Reference 1) established by the MPEG under theISO/IEC, a method for coding a moving picture of RGB format is provided.Here, a conventional method for coding and decoding RGB data by mappingthe RGB data to YUV data (where a G signal is mapped to a Y signal, a Bsignal is mapped to a U signal, and a R signal is mapped to a V signal)is provided.

However, in the conventional method, the RGB signal is coded and decodedusing the same method as the conventional method for coding and decodingYUV data. In the conventional coding of YUV data, the same intraprediction mode is used for coding U data and V data, whereas an intraprediction mode used for coding Y data is different from an intraprediction mode used for coding U data and V data. Therefore, whenmapping the YUV data to the RGB data, although the same intra predictionmode is used for R data and B data, an intra prediction mode used for Gdata is different from the intra prediction mode used for R data and Bdata.

In the conventional coding of the YUV data, a motion vector for Y datais used for motion compensation for the U data and the V data.Therefore, when mapping the YUV data to the RGB data, a motion vectorfor G data is used for motion compensation for the R data and the Bdata.

-   Non-Patent Reference 1: Draft of Version 4 of H.264/AVC (ITU-T-   Recommendation H.264 and ISO/IEC 14496-10 (MPEG-4 Part 10) Advanced    Video Coding, JVT-N050d1, Jan. 28, 2005)

DISCLOSURE OF INVENTION Problems that Invention is to Solve

Coding high-definition and high-quality pictures is becoming necessaryfor consumer-oriented devices, rather than for professional-use devices(television, camera, and the like). In the aforementioned conventionaltechnique, the 4:2:0 format or 4:2:2 format is used as the format of aYUV signal in most cases for the consumer-oriented devices. On the otherhand, the 4:4:4 format for an RGB signal is used for theprofessional-use devices in order to code high-definition andhigh-quality pictures. In a conventional technique of mapping RGB datato YUV data, it is difficult to code a 4:4:4 format picture for an RGBsignal without degrading its high definition and high quality.

Furthermore, in order to code/decoding processing on high-definitionpictures of RGB 4:4:4 format, it is possible to devise an apparatusstructure including three encoders and three decoders each of whichcorresponds to R data, G data, and B data, and operates in parallel.Even in this case, for the aforementioned conventional mappingtechnique, it is necessary to provide interface circuits in each of theencoders and the decoders in order to receive and pass, in each blockbetween the encoders, information, such as an intra-coded processingmethod and a motion vector. For this reason, there is a problem thatsuch structures of the encoders/decoders become complex, and the circuitscale increases.

The present invention is for solving the aforementioned problem, and theobject is to provide: stream data; a moving picture coding apparatusthat codes a picture made up of N component pictures; and a movingpicture decoding apparatus that decodes such picture, where N is aninteger that is 2 or greater, each apparatus having a simple hardwarestructure.

Means to Solve the Problems

In order to solve the aforementioned problem, the moving picture codingapparatus of the present invention includes: an obtainment unit thatobtains N color component pictures that compose one picture, where N isan integer that is 2 or greater; N coding units, each of which codes, inone of intra-picture prediction coding and inter-picture predictioncoding, a corresponding one of the N color component pictures, the Ncoding units being provided so as to correspond to the N color componentpictures; and a signal multiplexing unit that multiplexes N bit streamsoutputted from the N coding units into one bit stream signal, and thatoutputs the bit stream signal. With this structure, since one codingunit corresponds to one component picture, it is possible to efficientlycode a high-definition picture for professional use.

Here, each of the N coding units may independently determine aprediction mode to be used for the intra-picture prediction coding. Withthis structure, since each of the coding units performs intra-pictureprediction coding using a prediction mode independently determined,there is no need to pass, between the N coding units, prediction modesin each block. As a result, there is no need for each of the codingunits to include interfaces that pass prediction modes. When each of thecoding units is, for example, included in an LSI or a board, it ispossible to keep the increase of a circuit scale to the minimum, sincethere is no need to provide interface circuits that pass predictionmodes for each block.

Furthermore, since each of the coding units independently determine aprediction mode, it is possible to improve the coding efficiency in theintra-picture prediction coding.

Here, each of the N coding units may independently determine a motionvector to be used for the inter-picture prediction coding. With thisstructure, since each of the coding units performs inter-pictureprediction coding using an motion vector independently determined, thereis no need to pass, between the N coding units, prediction modes forinter-picture prediction coding. As a result, there is no need for eachof the coding units to include interfaces that pass prediction modes.When each of the coding units is, for example, included in an LSI or aboard, it is possible to keep the increase of a circuit scale to theminimum.

Here, each of the N coding units may independently determine aprediction mode to be used for the intra-picture prediction coding, oneof the N coding units may determine a motion vector to be used for theinter-picture prediction coding, and the N coding units may perform theinter-picture prediction coding by commonly using the motion vector.With this structure, it is possible to improve the coding efficiency inthe intra-picture prediction coding. Furthermore, one of the N codingunits has only to include a circuit (motion estimation circuit) thatdetermines a motion vector, and there is no need to include other codingunits. Generally, since a scale of the motion estimation circuit islarge, it is possible to reduce the circuit area of the other codingunits.

Here, it is possible that the N coding units individually use respectiveprediction modes or commonly use a prediction mode for the intra-pictureprediction coding, and the signal multiplexing unit may insert, in thebit stream signal, coding information indicating correspondence betweenthe N color component pictures and prediction modes to be used for theintra-picture prediction coding. With this structure, the moving picturedecoding apparatus can easily determine between which coding units fromamong the N coding units a common prediction mode is used for theintra-picture prediction coding, using the bit stream signal in whichthe coding information is inserted, and can simplify the decodingprocessing.

Here, the coding information may include the number of prediction modesand one or more of identifiers of the prediction modes, and the codinginformation may further include assignment information indicating colorcomponent pictures to which a common prediction mode is assigned whenthe prediction mode common to the color component pictures exists in thecoding information. With this structure, the moving picture decodingapparatus can simplify the decoding processing by determining the numberof prediction modes, one or more of identifiers of the prediction modes,and assignment information.

Here, the coding information may include a prediction mode flag, and theprediction mode flag may indicate one of: (a) that each of the N colorcomponent pictures has been coded in an independent prediction mode; (b)that the N color component pictures have been coded in a commonprediction mode; and (c) that two or more of the N color componentpictures have been coded in a common prediction mode and one or more ofthe N color component pictures other than the two or more of the N colorcomponent pictures has been coded in an independent prediction mode.This structure is appropriate for a coding method and a decoding methodeach of which selectively uses one of the (a) to (c). In such a case,the prediction mode flag may be 2 bits.

Here, the coding information may include a prediction mode flag, and theprediction mode flag may indicate one of: (a) that each of the N colorcomponent pictures has been coded in an independent prediction mode; and(b) that the N color component pictures have been coded in a commonprediction mode. This structure is appropriate for a coding method and adecoding method each of which selectively uses one of the (a) and (b).In such a case, the prediction mode flag may be 1 bit.

Here, the coding information may include a first prediction mode flag,the first prediction mode flag may indicate one of: (i) that two or moreof the N color component pictures have been coded in a common predictionmode and one or more of the N color component pictures other than thetwo or more of the N color component pictures has been coded in anindependent prediction mode; and (ii) a case other than (i), the codinginformation further includes a second prediction mode flag when thefirst prediction mode flag indicates (ii), and the second predictionmode flag may indicate one of: (a) that each of the N color componentpictures has been coded in an independent prediction mode; and (b) thatthe N color component pictures have been coded in a common predictionmode. This structure is appropriate for a coding method and a decodingmethod each of which selectively uses one of the (a), (b), and (i). Insuch a case, the prediction mode flag may be 1 bit or 2 bits.

Here, the N coding units may be N semiconductor integrated devices. Withthis structure, when the number of pixels of a picture is many (forexample, in the case of a super-high resolution picture having thedegree of resolution equal to or more than the HDTV, it is possible toefficiently code each of component pictures, even when it is difficultto code a picture using one coding unit.

Furthermore, the moving picture decoding apparatus of the presentinvention includes: a separation unit that separates a bit stream signalinto N bit streams corresponding to N color component pictures thatcompose one picture, where N is an integer that is 2 or greater, the bitstream signal indicating a coded moving picture; N decoding units, eachof which decodes, in one of intra-picture prediction decoding andinter-picture prediction decoding, a corresponding one of the N bitstreams, the N decoding units being provided so as to correspond to theN bit streams; and a picture multiplexing unit that multiplexes the Ncolor component pictures from the N decoding units into the one picture.

With this structure, there is no need to pass, between the N decodingunits, prediction modes for intra-picture prediction coding for eachblock. As a result, there is no need for each of the coding units toinclude interfaces that pass prediction modes. When each of the codingunits is, for example, included in an LSI or a board, it is possible tokeep the increase of a circuit scale to the minimum, since there is noneed to provide interface circuits that pass prediction modes for eachblock.

Here, each of the N decoding units may perform the intra-pictureprediction decoding in an independent prediction mode.

Here, each of the N decoding units may perform the inter-pictureprediction decoding using an independent motion vector.

Here, it is possible that each of the N decoding units may perform theintra-picture prediction decoding in an independent prediction mode, andthe N decoding units may perform the inter-picture prediction decodingusing a common motion vector.

Here, the separation unit may separate the bit stream signal into codinginformation indicating correspondence between the N color componentpictures and prediction modes to be used for the intra-pictureprediction decoding, and each of the N decoding units may perform theintra-picture prediction decoding according to the coding information.

Here, the coding information may include the number of prediction modesand one or more of identifiers of the prediction modes, and the codinginformation may further include assignment information indicating colorcomponent pictures to which a common prediction mode is assigned whenthe prediction mode common to the color component pictures exists in thecoding information.

Here, the coding information may include a prediction mode flag, and theprediction mode flag indicates one of: (a) that each of the N colorcomponent pictures has been coded in an independent prediction mode; and(b) that the N color component pictures have been coded in a commonprediction mode.

Here, the coding information may include a prediction mode flag, and theprediction mode flag may indicate one of: (a) that each of the N colorcomponent pictures has been coded in an independent prediction mode; (b)that the N color component pictures have been coded in a commonprediction mode; and (c) that two or more of the N color componentpictures have been coded in a common prediction mode and one or more ofthe N color component pictures other than the two or more of the N colorcomponent pictures has been coded in an independent prediction mode.

Here, the coding information may include a first prediction mode flag,the first prediction mode flag may indicate one of: (i) that two or moreof the N color component pictures have been coded in a common predictionmode and one or more of the N color component pictures other than thetwo or more of the N color component pictures has been coded in anindependent prediction mode; and (ii) a case other than (i), the codinginformation further includes a second prediction mode flag when thefirst prediction mode flag indicates (ii), and the second predictionmode flag may indicate one of: (a) that each of the N color componentpictures has been coded in an independent prediction mode; and (b) thatthe N color component pictures have been coded in a common predictionmode.

Here, the N decoding units may be N semiconductor integrated devices.

Furthermore, the stream data of the present invention includes N bitstreams and coding information, wherein the N bit streams represent Ncolor component pictures that compose one picture, where N is an integerthat is 2 or greater, and the coding information indicatescorrespondence between the N color component pictures and predictionmodes to be used for the intra-picture prediction decoding.

INDUSTRIAL APPLICABILITY

A moving picture coding apparatus, a moving picture decoding apparatus,and stream data according to the present invention have an effect thatcoding processing and decoding processing can be performed independentlyfor each signal so that the structures of the coding apparatus anddecoding apparatus can be simplified. They are useful as the movingpicture coding apparatus, the moving picture decoding apparatus, and thebit stream.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating an example of a structure of themoving picture coding apparatus according to the first embodiment of thepresent invention.

FIG. 2 is a block diagram illustrating a structure of a coding unit.

FIG. 3 is a schematic diagram illustrating a format of a RGB 4:4:4format.

FIG. 4 is a schematic diagram for describing an intra prediction mode.

FIG. 5A illustrates a data stream indicating mode information and threebit streams which are multiplexed on a macro block unit basis.

FIG. 5B illustrates a data stream indicating mode information and threebit streams which are multiplexed on a slice unit basis.

FIG. 5C illustrates a bit stream including information (a flag)indicating that the inter-picture prediction coding has beenindependently performed.

FIG. 5D illustrates a schematic diagram of a format of a data stream.

FIG. 5E illustrates a schematic diagram of a format of a data stream.

FIG. 6 is a block diagram illustrating a structure of a coding unit inthe first variation according to the first embodiment.

FIG. 7 is a block diagram illustrating an example of a structure of themoving picture coding apparatus in the second variation according to thefirst embodiment.

FIG. 8 is a block diagram illustrating an example of a structure of acoding unit that codes a G signal.

FIG. 9 is a block diagram illustrating an example of a structure of acoding unit that codes a R (or B) signal.

FIG. 10 is a block diagram showing an example of a structure of themoving picture coding apparatus in the second embodiment.

FIG. 11 is a block diagram illustrating a structure of a coding unit.

FIG. 12 illustrates prediction modes for the intra prediction mode.

FIG. 13A illustrates a format of a data stream.

FIG. 13B illustrates a format of a data stream.

FIG. 13C illustrates a format of a data stream.

FIG. 13D illustrates a format of a data stream.

FIG. 13E describes an example of a prediction mode flag.

FIG. 13F describes an example of a prediction mode flag.

FIG. 13G describes an example of a prediction mode flag.

FIG. 14 is a block diagram showing an example of a structure of themoving picture decoding apparatus in the third embodiment.

FIG. 15 is a block diagram showing a structure of a decoding unit.

FIG. 16 is a block diagram showing another structure of a decoding unit.

FIG. 17 is a block diagram illustrating a structure of a video camera asan application example of the present invention.

NUMERICAL REFERENCES

100 Moving picture coding apparatus

101 Signal separation unit

102, 103, 104 Coding unit

105 Bit stream multiplexing unit

106 Control unit

1000 Moving picture decoding apparatus

1001 Variable length decoding unit

1002, 1003, 1004 Decoding unit

1005 Signal multiplexing unit

1010 Probability table holding unit

Best Mode for Carrying Out the Invention

(First embodiment)

The present embodiment describes a moving picture coding apparatusincluding: an obtainment unit that obtains N component pictures thatcompose one picture, where each of the component pictures has an equalnumber of pixels and N is an integer that is 2 or greater; N codingunits, each of which codes, in intra-picture prediction coding, acorresponding one of the N component pictures, the N coding units beingprovided so as to correspond to the N color component pictures; and asignal multiplexing unit that multiplexes N bit streams outputted fromthe N coding units into one bit stream signal. The each of the N codingunits independently determines a prediction mode to be used for theintra-picture prediction coding. Since one coding unit corresponds toone component picture and each of the coding units independentlydetermines a prediction mode for the intra-picture prediction coding, itis possible to efficiently code a high-definition picture forprofessional use. N is assumed to be three in the following descriptionso as to correspond to RGB.

FIG. 1 is a block diagram showing an example of a structure of themoving picture coding apparatus according to the first embodiment of thepresent invention. A moving picture coding apparatus 100 includes asignal separation unit 101, three coding units 102, 103 and 104, a bitstream multiplexing unit 105, and a control unit 106.

An input signal IN is inputted to the signal separating unit 101. Theinput signal IN is a moving picture signal of RGB 4:4:4 format. Here, asshown in FIG. 3, the RGB 4:4:4 format is a format in which each pixel isdescribed as a combination of three pixels of R signal, G signal and Bsignal, and in which each of the R signal, G signal and B signal withina picture has equal number of pixels. For example, in the case whereeach color pixel of the R signal, G signal and B signal is indicated by8 bits, one pixel of the RGB signal is indicated by 24 bits.

The input RGB signal IN inputted to the signal separation unit 101 isseparated into three signals: an input signal (input picture) IN_Rincluding only R signal; an input signal (input picture) IN_G includingonly G signal; and an input signal (input picture) IN_B including only Bsignal. The separated three signals are respectively inputted to thecoding units 102, 103 and 104.

FIG. 2 shows a structure of each of the coding units 102, 103 and 104.Hereafter, the operation of the coding unit 102 is described which codesthe input signal IN_R. However, the structure and the operation arecommon to the coding unit 103 which codes the input signal IN_G and tothe coding unit 104 which codes the input signal IN_B.

As shown in FIG. 2, the coding unit 102 includes a frame memory 201, asubtracting unit 202, a frequency transform unit 203, a quantizationunit 204, a variable length coding unit 205, an inverse quantizationunit 206, an inverse frequency transform unit 207, an adding unit 208, areference picture memory 209, an intra prediction mode determinationunit 210, an intra prediction unit 212, a control unit 216 and aprobability table holding unit 217.

The coding unit 102 codes each picture of the input pictures IN_Rs as anintra-picture prediction coded (Intra) picture.

The input picture IN_R is stored in the frame memory 201 and thenoutputted from the frame memory 201 on a block unit basis (e.g. in aunit of macro block having horizontal 16 pixels and vertical 16 pixels).

The macro block outputted from the frame memory 201 is inputted to theintra prediction mode determination unit 210. The intra prediction modedetermination unit 210 determines how to perform intra-pictureprediction coding on the inputted macro block. More specifically, theintra prediction mode determination unit 210 determines an intraprediction block size of the inputted macro block and an intraprediction mode for each block. The intra prediction block size is oneof the following sizes: horizontal 4 pixels×vertical 4 pixels;horizontal 8 pixels×vertical 8 pixels; and horizontal 16 pixels×vertical16 pixels. The intra prediction mode is determined in accordance with anintra prediction mode specified by the MPEG-4 AVC standard.

FIG. 4 is a schematic diagram illustrating an intra-picture predictionmode specified by the MPEG-4AVC standard. In the diagram, it is assumedthat peripheral pixels (pixels above the dotted line) to be used for theintra-picture prediction have already been coded and stored in thereference picture memory 209. Black circles of a pixel group 402 in FIG.4 are used for performing the intra-picture prediction on an intraprediction current block 401 of 4 pixels×4 pixels. An intra predictionmode is determined for each block. For example, a prediction mode isdetermined from among nine different intra prediction modes for a blockof horizontal 4 pixels×vertical 4 pixels. Furthermore, a prediction modeis determined from among four different intra prediction modes for ablock of horizontal 16 pixels×vertical 16 pixels. FIG. 12 illustratesprediction modes for an intra prediction block of horizontal 4pixels×vertical 4 pixels.

One of a block size of: horizontal 4 pixels×vertical 4 pixels;horizontal 8 pixels×vertical 8 pixels; and horizontal 16 pixels×vertical16 pixels is determined as an intra prediction size.

FIG. 12 is a schematic diagram illustrating prediction directions usingthe pixel group 402 shown in FIG. 4. A prediction mode 0 is a mode inwhich pixels underneath the pixel group 402 are predicted in a verticaldirection. Similarly, as each prediction direction: a prediction mode 1indicates a horizontal direction; a prediction mode 3 indicates adiagonal down left direction; a prediction mode 4 indicates a diagonaldown right direction; a prediction mode 5 indicates a vertical rightdirection; a prediction mode 6 indicates a horizontal down direction;and a prediction mode 7 indicates a vertical right direction. The mode 2indicates not a direction but an average as a prediction value. Notethat there are four different intra prediction modes for a block ofhorizontal 16 pixels×vertical 16 pixels.

An intra prediction mode (IPM) determined by the intra prediction modedetermination unit 210 is outputted to the intra prediction unit 212 andthe variable length coding unit 205. The intra prediction unit 212determines an intra prediction block size and a prediction mode for eachblock, based on the intra prediction mode IPM determined by the intraprediction mode determination unit 210. Furthermore, the intraprediction unit 212 generates an intra prediction picture IP byobtaining an intra reference pixel from the reference picture memory209, and outputs the generated IP to the subtracting unit 202.

The subtracting unit 202 receives the macro block of the input picturefrom the frame memory 201 and the intra predictive image IP generated bythe intra prediction unit 212, generates a differential image betweenthe input picture and the intra predictive image IP, and outputs thedifferential image to the frequency transform unit 203.

The frequency transform unit 203 performs frequency transformation onthe differential image generated by the subtracting unit 202, andoutputs frequency transform coefficients.

The quantization unit 204 performs quantization of the frequencytransform coefficients generated by the frequency transform unit 203,and outputs the quantized frequency transform coefficients QT. Here, thequantization is a process of dividing the frequency transformcoefficients by a predetermined value (quantization step). It is assumedthat this quantization step is given by the control unit 216 (thequantization step may be included in a control signal CTL from thecontrol unit 106). The quantized frequency transform coefficients QT areoutputted to the variable length coding unit 205 and the inversequantization unit 206.

The quantized frequency transform coefficients QT are processed ininverse quantization by the inverse quantization unit 206, are furtherprocessed in inverse frequency transformation by the inverse frequencytransform unit 207, and become a decoded differential image LDD. Thedecoded differential image LDD is added to the intra predictive image IPin the adding unit 208, becomes a decoded image LD, and stored in thereference picture memory 209. The decoded image LD stored in thereference picture memory 209 is used in the later coding as a referencepicture.

The variable length coding unit 205 performs variable length coding onthe quantized frequency transform coefficients QT inputted from thequantization unit 204, an intra prediction mode IPM inputted from theintra prediction mode determination unit 210 and the like, and outputs abit stream ST_R.

Here, as a method for the variable length coding method used in thevariable length coding unit 205, there is a context adaptive arithmeticcoding method adopted in the international standard moving picturecoding method H.264. The context adaptive arithmetic coding method is amethod for switching the probability tables used for arithmetic codingaccording to the variable length coding target data and data on whichthe variable length coding has already been performed (contextadaptation). For example, as a context for performing variable lengthcoding of the quantized frequency transform coefficients QT, a blocksize for intra prediction and a block size for frequency transformationand the like are used. Here, it is assumed that the probability tablesare held in the probability table holding unit 217.

The coding units 102, 103 and 104 respectively output the bit streamsST_R, ST_G and ST_B, and input them to the bit stream multiplexing unit105. The bit stream multiplexing unit 105 multiplexes the inputted threebit streams ST_R, ST_G and ST_B into one bit stream ST, and outputs theST. In this case, the bit stream multiplexing unit 105 inserts, into abit stream signal, mode information indicating a prediction mode of acomponent picture. As a method for multiplexing three bit streams andmode information into a bit stream, there are methods, such as a methodfor multiplexing data on a block or a macro block unit basis and on apicture or a slice unit basis. Examples of such multiplexing areillustrated in FIGS. 5A and 5B.

FIG. 5A illustrates a data stream indicating mode information and threebit streams which are multiplexed on a macro block unit basis. As such,the multiplexing method on a block or macro block unit basis has aneffect of having an almost the same bit stream structure as the bitstream structure of the conventional bit stream obtained by coding theYUV pictures.

FIG. 5B illustrates a data stream indicating mode information and threebit streams which are multiplexed on a slice unit basis. Furthermore,when multiplexing data on a picture or slice unit basis, a unit formultiplexing becomes larger. As a result, there is an effect that thenumber of switching processes of bit streams for the multiplexingprocessing can be reduced, and the multiplexing processing can besimplified.

Furthermore, information (flag) indicating that each of the R, G, and Bsignals is independently coded may be described in the bit stream. Thisinformation may be a flag indicating that a prediction mode isindependently determined for intra-picture prediction, and may beinformation, in the bit streams, indicating a prediction mode forperforming intra-picture prediction on RGB signals. The information(flag) has only to be described in a header of the whole sequence or inan additional information unit. FIG. 5C shows an example of a structureof the bit stream for this case. With this, when a decoding apparatusdecodes the bit stream, it can be easily judged whether or not each ofthe RGB signals can be decoded individually.

As described in the above, the moving picture coding apparatus of thepresent invention separates an input moving picture of RGB 4:4:4 formatinto R signal, G signal and B signal, and performs intra-pictureprediction coding on each of the signals, using respective coding unitsfor each signal. Herein, in the intra prediction at the time of codingeach signal, an intra prediction mode is determined respectively foreach signal. Further, in variable length coding using arithmetic codingwhen coding each signal, a probability table is held respectively byeach signal (a probability table is not commonly used among signals).

Through such operations, coding can be performed completelyindependently for each signal (coding units do not need to transferdata, information and the like mutually each other) so that thestructure of the coding apparatus can be simplified without reducing thecoding efficiency. For example, in the case where it is difficult toprocess for single coding apparatus a very large number of pixels of aninput signal (e.g. in the case where the input picture has pixels equalto or more than the pixels in the HDTV picture), the present inventionis very useful. Also, in this case, each of the RGB signal has the samenumber of pixels so that the respective coding units of each signal canhave the same hardware structure. Furthermore, in the case where theintra prediction mode is determined respectively for each signal,information indicating the intra prediction mode is respectivelydescribed in each signal as a bit stream structure. Accordingly, the RGBsignals can be decoded respectively also when decoding the bit stream sothat there is an effect that the decoding process is simplified.

It should be noted that, while in the present embodiment, the inputpicture of RGB 4:4:4 format, that is a picture having three colorelements, is described, coding process can be performed in the samestructure for the number of color elements even in the case where thecolor elements include other than the three colors (e.g. four colors,six colors and the like). Therefore, the same effect as obtained in thepresent embodiment can be obtained.

(First variation)

The first variation according to the first embodiment is to bedescribed. In this variation, a moving picture coding apparatusincluding three coding units each of which can perform not onlyintra-picture prediction coding but also inter-picture prediction codingis to be described. In coding of a moving picture, each of the threecoding units independently determines a prediction mode forintra-picture prediction coding, and independently determines a motionvector for inter-picture prediction coding.

The moving picture coding apparatus according to the first variationfurther includes coding units 102 a, 103 a, and 104 a, instead of thecoding units 102, 103, and 104. The coding units 102 a, 103 a, and 104 aselectively perform the intra-picture prediction coding andinter-picture prediction coding.

FIG. 6 is a block diagram illustrating a structure of the coding unit102 a (or one of coding units 103 a and 104 a). The coding unit 102 aincludes a motion estimation unit 611, a motion compensation unit 613,switches 614 and 615, and a coding mode determination unit 618, inaddition to the units of the coding unit 102 shown in FIG. 2.

The coding unit 102 a is different from the coding unit 102 in that thecoding unit 102 codes each picture of the input pictures IN_R as anintra-picture prediction coded picture, whereas the coding unit 102 acodes each picture of the input pictures IN_R as an inter-pictureprediction coded picture.

A processing method used in the coding unit 102 a when coding eachpicture of the input pictures IN_R as an intra-picture prediction codedpicture is the same as the processing method described in the firstembodiment. Therefore, the description is omitted here.

An operation when coding a picture of the input pictures IN_Rs as aninter-picture prediction coded picture is described hereinafter.

The input pictures IN_Rs are first stored in the frame memory 201, andthen outputted from the frame memory 201 on a block unit basis (e.g. ina unit of macro block having horizontal 16 pixels and vertical 16pixels).

The macro block outputted from the frame memory 201 is inputted to theintra prediction mode determination unit 210 (the switch 614 isconnected to “a” by the control unit 216). In this case, since theoperations in the intra prediction mode determination unit 210 and theintra prediction unit 212 are the same as those in the first embodiment,the description is omitted. The intra prediction mode is outputted tothe intra prediction unit 212 and the coding mode determination unit618.

The macro block again outputted from the frame memory 201 is inputted tothe intra prediction mode determination unit 611 (the switch 614 isconnected to “b” by the control unit 216). The motion estimation unit611 estimates, for the inputted macro block, the motion amount (motionvector) with respect to the reference picture (a coded picture that isheld in the reference picture memory 209 and is different from thepicture to be coded). In the motion estimation, generally, the motionvector having the minimum weighted sum of: a differential value betweenthe block to be coded and a predictive image (an image in the referencepicture referred by the motion vector); and an amount of codes for themotion vector is selected. The estimated motion vector is outputted tothe motion compensation unit 613 and the coding mode determination unit618.

The motion compensation unit 613 generates a predictive image MP byobtaining inter reference pixels from the reference picture memory 209based on the motion vector determined by the motion estimation unit 611,and outputs the predictive image MP to the subtracting unit 202 (theswitch 615 is connected to “b” by the control unit 216).

The processing performed by the subtracting unit 202, the frequencytransform unit 203, the quantization unit 204, the inverse quantizationunit 206, the inverse frequency transform unit 207, and the adding unit208 is the same as the processing described in the first embodiment.Therefore, the description about the processing is omitted here.

The coding mode determination unit 618 determines a coding mode of amacro block to be coded using outputs from the intra prediction modedetermination unit 210, motion estimation unit 611, quantization unit204, frame memory 201, and adding unit 208, and the like. Here, it isdetermined which one of the intra-picture prediction coding and theinter-picture prediction coding is used for coding the macro block to becoded. In general, the coding mode having the small weighted sum of theamount of bits to be generated and the coded distortion is selected. Inthe case where the intra-picture prediction coding is selected as thecoding mode, the information indicating the intra prediction mode IPM isoutputted to the variable length coding unit 205. In the case where theinter-picture prediction coding is selected as a coding mode, the motionvector MV and the coding mode MD are outputted to the variable lengthcoding unit 205.

The variable length coding unit 205 performs variable length coding on:the quantized frequency transform coefficients QT inputted from thequantization unit 204; and the coding mode MD, and the intra predictionmode IPM or the motion vector MV which are outputted from the codingmode determination unit 618, and outputs the bit stream ST_R.

Here, in the case where the variable length coding unit 205 codes themotion vector MV using a context adaptive arithmetic coding method, amethod for changing a probability table depending on a size (context) ofthe motion vector of the coded peripheral block can be used. Here, it isassumed that the probability tables are held in the probability tableholding unit 217.

The bit streams ST_R, ST_G, and ST_B respectively outputted from thecoding units 102 a, 103 a, and 104 a are inputted to the bit streammultiplexing unit 105. The bit stream multiplexing unit 105 multiplexesthree bit streams ST_R, ST_G, and ST_B into one bit stream ST, andoutputs the bit stream ST. Here, as a method for multiplexing three bitstreams into one bit stream, there are a method for multiplexing bitstreams in a unit of block or macro block, and a method for multiplexingbit streams in a unit of picture or slice.

FIG. 5D illustrates a data stream in which motion vector information andthree bit streams are multiplexed on a macro unit basis. In the casewhere the bit streams are multiplexed in a unit of block or macro block,there is an effect that the multiplexed bit stream has the samestructure as the bit stream obtained by coding the conventional YUVpictures. Furthermore, the bit streams may be multiplexed on a pictureor a slice unit basis. In this case, since the unit for multiplexingbecomes large, there is an effect that the number of switching processesof bit streams for the multiplexing processing can be reduced, and themultiplexing processing can be simplified. The bit stream structureherein is the same as the structure shown in FIG. 5B, and motion vectorinformation is inserted in each slice header.

Further, information (flag) indicating that each of the R, G, and Bsignals is independently coded (indicating that a motion vector isdetermined independently or indicating that the motion vector for eachsignal is respectively described in the bit stream) may be described inthe bit stream. The information (flag) has only to be described in aheader of a whole sequence or an additional information unit. FIG. 5Cshows an example of a bit stream structure for this case. Accordingly,when the decoding apparatus decodes the bit stream, whether it candecode each of the RGB signals independently can be easily judged.

As described in the above, the moving picture coding apparatus of thepresent invention receives a moving picture of RGB 4:4:4 format as aninput picture, separates R signal, G signal and B signal from the inputsignal, and performs intra prediction coding of each signal usingrespective coding unit for each signal. Herein, the motion vector usedfor motion prediction for coding each signal is determined independentlyfor each signal. Further, in the case where arithmetic coding is usedfor variable length coding for coding each signal (e.g. when the motionvector is coded), a probability table is held respectively by eachsignal (a probability table is not commonly used among signals).

Through such operations, coding can be performed completelyindependently for each signal (coding units do not need to transferdata, information and the like mutually each other). Therefore, in thecase where single coding apparatus cannot perform coding because thenumber of pixels to be processed is very large as in the moving picturehaving the degree of resolution equal to or more than the HDTV, thecoding process can be realized in real time by coding each signal inparallel. Also, the structure of the coding apparatus and the processingdetails herein can be simplified. Also, in this case, each of the RGBsignal has the same number of pixels so that the respective coding unitof each signal can have the same hardware structure. Furthermore, in thecase where the motion vector is determined respectively for each signal,information indicating the motion vector is respectively described ineach signal within a bit stream. Accordingly, the RGB signals can bedecoded respectively when decoding the bit stream so that there is aneffect that the decoding process is simplified.

(Second variation)

In the first variation, the moving picture coding apparatus in that eachof the three coding units independently determines a prediction mode forintra-picture prediction coding and independently determines a motionvector for inter-picture prediction coding is described. In the presentvariation, the moving picture coding apparatus in that one of the threecoding units determines a motion vector for inter-picture predictioncoding and the inter-picture prediction coding is performed by commonlyusing the motion vector determined by the three coding units is to bedescribed. The second variation is the same as the first variation inthat the each of the three coding units independently determines aprediction mode for intra-picture prediction coding.

FIG. 7 is a block diagram showing an example of a structure of themoving picture coding apparatus in the second variation. The movingpicture coding apparatus 100 b has almost the same structure as that ofthe moving picture coding apparatus 100 described in the firstembodiment. However, it differs from the moving picture coding apparatus100 in that the moving picture coding apparatus 100 b includes thecoding units 102 b, 103 b, and 104 b instead of the coding units 102,103, and 104, and the coding units 102 b, 103 b, and 104 b passinformation each other. Furthermore, the structures are slightlydifferent between the coding unit 103 b which processes a G signal andthe coding units 102 b and 104 b which process other signals (R signaland B signal). In other words, the structure of the second variationspecifies that the coding unit 103 b which processes a G signal notifiesthe coding units 102 b and 104 b which process other signals (R signaland B signal) respectively of a coding mode MD indicating either theintra-picture prediction coding or inter-picture prediction coding, andof a motion vector MV used for the inter-picture prediction coding.

FIG. 8 is a block diagram showing an example of a structure of thecoding unit 103 b which codes the G signal. The coding unit 103 b hasthe same structure as the coding unit 102 a shown in FIG. 6 according tothe first embodiment. However, it differs in that it outputs the codingmode MD and motion vector MV (only in the case of inter-pictureprediction mode) that are determined by the coding mode determinationunit 618, to the coding units 102 b and 104 b.

FIG. 9 is a diagram showing an example of a structure of the coding unit102 b (or 104 b) which codes the R signal (or B signal). The coding unit102 b has the same structure as the coding unit 102 a shown in FIG. 6according to the first embodiment. However, the following two points aredifferent. First, it does not have the motion estimation unit 611.Second, it performs coding using the coding mode MD and motion vector MV(only in the case of inter-picture prediction coding mode) that areinputted from the coding unit 103 b to the control unit 219. The detailsare described in the following.

In the case where the coding mode MD is the intra-picture predictioncoding mode, the intra prediction mode determination unit 210 determinesthe intra prediction mode, and the inter prediction unit 212 generatesthe inter predictive image (the switch 615 is connected to “a”). Themethod for coding the differential image between the input picture andthe predictive image is the same as the method described in the firstembodiment. The intra prediction mode IPM is outputted to the variablelength coding unit 205 and is described in the bit stream.

In the case where the coding mode MD is the inter-picture predictioncoding mode, the motion vector MV is outputted to the compensation unit613. Also, the switch 615 is connected to “b”. The motion compensationunit 613, based on the inputted motion vector, obtains inter-picturereference pixels from the reference picture memory 209, generates apredictive image MP, and outputs the predictive image MP to thesubtracting unit 202 via the switch 615. The method for coding thedifferential image between the input picture and the predictive image isthe same as the method described in the first embodiment. However, thecoding mode MD and the motion vector MV are not described in the bitstream (the coding mode MD and the motion vector MV are described in thebit stream ST_G outputted by the coding unit 103 b).

The bit streams ST_R, ST_G and ST_B outputted from the coding units 102b, 103 b and 104 b are inputted to the bit stream multiplexing unit 105.The bit stream multiplexing unit 105 multiplexes the inputted three bitstreams ST_R, ST_G and ST_B into one bit stream and outputs the bitstream. Here, as a method for multiplexing the three bit streams intoone bit stream, there are methods, such as a method for multiplexing bitstreams in a unit of block or macro block and a method for multiplexingbit streams in a unit of picture or slice. In the case where the bitstreams are multiplexed in a unit of block or macro block, there is aneffect that the multiplexed bit stream has the same bit stream structureas the bit stream obtained by coding the conventional YUV pictures. FIG.5E shows an example of a bit stream structure for this case. In thiscase, the order within the bit stream is changed so that the coding modeMD and the motion vector MV described in the bit stream ST_G aredescribed in a head of a block or a macro block. Also, when multiplexingbit streams in a unit of picture or slice, since the unit for themultiplexing processing becomes large, there is an effect that thenumber of switching processes of bit streams for the multiplexingprocessing can be reduced, and the multiplexing processing can besimplified. The bit stream structure herein is the same as the structureshown in FIG. 5B. Further, information (flag) may be described in thebit stream, the information indicating that the intra prediction isdetermined independently for each of the RGB signals (an intraprediction mode for each signal is independently described in the bitstream); and the motion vector is commonly used by the RGB signals (thecommon motion vector for the RGB signals is described in the bitstream). The information (flag) has only to be described in a header ofthe whole sequence or in the additional information unit. FIG. 5C showsan example of a bit stream structure for this case. Accordingly, whenthe decoding apparatus decodes the bit stream, it can be easily judgedthat the intra prediction is independently described for each signal andthe motion vector is commonly used by the signals and described.

As described in the above, the moving picture coding apparatus of thepresent invention receives a moving picture of RGB 4:4:4 format as aninput picture, separates the input signal into an R signal, a G signaland a B signal, and codes each signal using the intra-picture predictioncoding and the inter-picture prediction coding. Herein, the coding mode(indicating which one of the intra-picture prediction coding and theinter-picture prediction coding is used) determined by the first signal(e.g. G signal) is also used for coding the second signal (e.g. R signaland B signal). In the case where the coding mode is the intra-pictureprediction coding, the intra picture prediction method is determinedindependently for each signal. Further, in the case where theinter-picture prediction coding, the motion vector determined for thefirst signal (G signal) is used. Then, the coding mode and the motionvector determined for the first signal on one coding unit basis (e.g.macro block) are only described in the stream data. Also, the intraprediction mode determined for each signal is described in the bitstream.

Through such operation, in the intra-picture prediction coded macroblock within the intra-picture prediction coded picture or within theinter-picture prediction coded picture, coding is performed completelyindependently for each signal, while in the inter-picture predictioncoded macro block, the motion vector determined for the first signal iscommonly used. In general, in the intra-picture prediction coded macroblock, while the amount of codes for the quantization frequencytransform coefficients occupies a considerable amount of codes to begenerated, the amount of information of the intra prediction mode issmall. In addition, the amount of processing for determining the intraprediction mode is relatively small. Further, in the inter-pictureprediction coded macro block, the amount of codes for the motion vectorhas the high percentage of the total amount of codes to be generated.Further, in the inter-picture prediction coding, the amount ofprocessing for the motion estimation occupies the majority of the totalamount of processing. Therefore, in the processing of the presentintra-picture coded picture, the structure (processing) of the codingapparatus can be simplified without reducing the coding efficiency. Atthe same time, in the processing of inter-picture prediction codedpicture, although the structure (processing) of the coding apparatus isslightly complicated (because communication among coding units ofrespective signals is necessary), the amount of processing for thecoding units as a whole can be largely reduced (because the processingof motion estimation is performed only on one signal), and the codingefficiency can be increased (because the number of motion vectorsdescribed in the bit stream becomes less).

It should be noted that, in the second variation, the coding mode andmotion vector obtained in the coding process of a G signal are used forcoding other signals (R signal and B signal). However, the coding modeand the motion vector can be determined using the R signal and B signal,and the similar effect as in the present invention can be obtained forthis case.

Furthermore, although the present embodiment describes a case where apicture of RGB 4:4:4 format is used, the present invention can beapplied even in the case where the picture is in RGB 4:2:2 format or inRGB 4:2:0 format.

(Second embodiment)

The present embodiment describes a moving picture coding apparatusincluding: three coding units in which prediction modes forintra-picture prediction coding are used individually or a predictionmode is used commonly; and a signal multiplexing unit that inserts, intoa bit stream signal, coding information indicating correspondencebetween three component pictures and the prediction modes for theintra-picture prediction coding. For prediction coding, this movingpicture coding apparatus selects one of the following: (1) each of threecoding units independently determines a prediction mode; (2) two codingunits use a common prediction mode and one coding unit uses anindependent prediction mode; and (3) three coding units commonly use aprediction mode. Furthermore, for notifying a decoding apparatus of oneof (1) to (3), the coding information includes the number of predictionmodes and one or more of identifiers of the prediction modes, andfurther includes assignment information indicating component pictures towhich a common prediction mode is assigned when the prediction modecommon to the color component pictures exists in the coding information.

FIG. 10 is a block diagram illustrating an example of a structure of themoving picture coding apparatus in the second embodiment. The movingpicture coding apparatus 100 c has almost the same structure as that ofthe moving picture coding apparatus 100 described in the firstembodiment. However, it differs from the moving picture coding apparatus100 in that the moving picture coding apparatus 100 c includes thecoding units 102 c, 103 c, and 104 c instead of the coding units 102,103, and 104, and the coding units 102 c, 103 c, and 104 c passinformation each other. The coding units 102 c, 103 c, and 104 c havethe same structure, and they notify a coding mode MD indicating eitherthe intra-picture prediction coding or inter-picture prediction coding,a motion vector MV used for the inter-picture prediction coding, and aprediction mode IPM for the intra-picture prediction coding each other.

FIG. 11 is a block diagram illustrating a structure of the coding unit102 c (alternatively, 103 c or 104 c). The diagram differs from FIG. 8in: that the coding mode determination unit 618 transmits, to the codingunits 103 c and 104 c, the prediction mode IPM for the intra-pictureprediction coding, in addition to the coding mode MD and the motionvector MV; that a control unit 218 receives, from the coding units 103 cand 104 c, the prediction mode IPM for the intra-picture predictioncoding; and the operation in the control unit 218.

The control unit 218 independently determines, according to anextraneous instruction or a predetermined setting, a prediction mode forthe intra-picture prediction coding, or determines a prediction modecommonly used with other coding units. When the prediction mode iscommonly used with other coding units, it is determined whether thecommon prediction mode is determined and transmitted to other codingunits, or the common prediction mode determined by other coding units isreceived and used. One of nine prediction modes is determined as theprediction mode for the intra-picture prediction coding in the case of ablock size of 4 pixels×4 pixels as shown in FIG. 12.

Furthermore, the bit stream multiplexing unit 105 multiplexes the codinginformation into a data stream. This coding information includes thenumber of prediction modes and an identifier corresponding to theprediction mode, and further includes assignment information indicatinga component picture that commonly allocates a prediction mode when aprediction mode commonly used exists in the component picture.

FIG. 13A illustrates a format of a data stream in which codinginformation and three bit streams are multiplexed when each of the threecoding units independently determines a prediction mode as described inabove (1). The stream data in the diagram includes the number ofprediction modes (number identifier) 610, and prediction modeidentifiers (prediction mode) 620R, 620G, and 620B. In this case, thenumber of prediction modes 610 is 3, indicating that each of the threecoding units independently uses a prediction mode. The number ofprediction modes 610 may be inserted in a data stream on a macro block,slice, or picture unit basis, and may be applied to macro blocksfollowing the inserted macro block as in the diagram. The predictionmode identifiers 620R, 620G, and 620B are respectively provided forthree components of the macro block for every coding data.

FIG. 13B illustrates a format of a data stream in which codinginformation and three bit streams are multiplexed when the three codingunits uses a common prediction mode as described in above (3). Thestream data includes the number of prediction modes 610 and a predictionmode identifier 620C. In this case, the number of prediction modes is 1,indicating that one common prediction mode is used among the threecoding units. The prediction mode identifier 620C indicates a commonprediction mode, and is provided in a head of three component codingdata.

FIG. 13C illustrates a format of a data stream in which codinginformation and three bit streams are multiplexed when the two codingunits uses a common prediction mode and one coding unit uses anindependent prediction mode, as described in above (2). The stream datain the diagram includes the number of prediction modes 610, assignmentinformation 650, and prediction mode identifiers 620 a and 620 b. Inthis case, the number of prediction modes 610 is 2, indicating that onecommon prediction mode is used between two coding units and the othercoding unit independently uses one prediction mode. The prediction modeidentifiers 620 a and 620 b indicate respective prediction modes. Theassignment information 650 indicates correspondence between theprediction modes indicated by the prediction mode identifiers 620 a and620 b and component coding data. For example, the assignment information650 indicates that the prediction mode indicated by the prediction modeidentifier 620 a is common to component coding data 630R and 630G, andthe prediction mode indicated by the prediction mode identifier 620 b isused by component coding data 630B.

FIG. 13D illustrates a data stream in which the intra-picture predictioncoding in three coding units has been changed from the above (3) to (1)on the way. As such, the intra coding may be changed dynamically.

As described above, according to the moving picture coding apparatus ofthe present embodiment, it is possible to select whether the threecoding units can use a prediction mode commonly or individually useprediction modes, for the intra-picture prediction coding. One of theabove (1) to (3) may be determined in advance, or may be adaptivelyselected according to details of a moving picture (a motion amount andcomplexity of a picture).

Note that although the second embodiment describes the moving picturecoding apparatus that can adaptively set whether a prediction mode forthe intra-picture prediction coding is independently determined in eachof the three coding units or commonly used in the three coding units,whether a motion vector for the inter-picture prediction coding isindependently determined in each of the three coding units or commonlyused in the three coding units may be adaptively set.

Furthermore, although the second embodiment describes a case wherecoding information includes the number of prediction modes and one ormore of identifiers of the prediction modes, when the bit streammultiplexing unit 105 multiplexes the coding information into a datastream, it may include a predetermined prediction mode flag instead ofthe number of prediction modes. Here, the prediction mode flag is a flagindicating which one of (1) to (3) is used. Although (1) to (3) aredescribed in view of the coding apparatus, in view of stream data, (1)indicates that each of the three component pictures is coded in anindependent coding mode. Furthermore, (2) indicates that two componentpictures are coded in a common prediction mode, and one componentpicture is coded in an independent prediction mode. (3) indicates thatthree color component pictures are coded in a common prediction mode.There are plural methods for representing prediction mode flags.

In the first method for representing a prediction mode flag, theprediction mode flag indicates one of (1) and (3). FIG. 13E illustratesan example of a representation of a flag (Flag_a) in the first method.As in the diagram, the value of Flag_a is 0 in the case of (1) and 1 inthe case of (3). In this case, the structure of a coding stream becomessimilar to FIGS. 13A, 13B, and 13D. The first method is appropriate as acoding method and a decoding method using above (1) or (3) without using(2). In such a case, the prediction mode flag may be 1 bit.

In the second method for representing a prediction mode flag, theprediction mode flag indicates one of (1) to (3). FIG. 13F illustratesan example of a representation of a flag (Flag_b) in the second method.As in the diagram, the value of Flag_b is 0 in the case of (1), 1 in thecase of (2), and 2 in the case of (3). In this case, the structure of acoding stream becomes similar to FIGS. 13A, 13B, 13C and 13D. The secondmethod is appropriate as a coding method and a decoding method,selectively using one of (1) to (3). In such a case, the prediction modeflag may be 2 bits.

In the third method for representing a prediction mode flag, theprediction mode flag indicates two steps (two flags). FIG. 13Gillustrates an example of a representation of a flag (Flag_c1,Flag_c2)in the third method. For example, as shown in FIG. 13G, the firstprediction mode flag Flag_c1 indicates (2) or other methods (in otherwords, (1) or (3)), when the first prediction mode flag is other than(2). Further, the second prediction mode flag Flag_c2 indicates either(1) or (3). When the first prediction mode flag Flag_c1 indicates (2),the second prediction mode flag Flag_c2 can be omitted. The third methodis appropriate as a coding method and a decoding method, selectivelyusing one of (1) to (3). In such a case, the prediction mode flag may be1 bit or 2 bits.

(Third embodiment)

In the present embodiment, a moving picture decoding apparatuscorresponding to the moving picture coding apparatus in FIG. 1 describedin the first embodiment is to be described.

FIG. 14 is a block diagram illustrating an example of a structure of themoving picture decoding apparatus of the present invention. The movingpicture decoding apparatus 1000 includes a variable length decoding unit1001, three decoding units 1002, 1003 and 1004, a signal multiplexingunit 1005, and a probability table holding unit 1010.

A bit stream ST is inputted to the variable length decoding unit 1001.It is assumed that the bit stream ST is obtained by coding a movingpicture signal of RGB 4:4:4 format and is the bit stream generated bythe moving picture coding apparatus described in the first embodiment.

The bit stream ST inputted to the variable length decoding unit 1001 isvariable-length decoded. The examples of the bit stream herein are shownin FIG. 5A and FIG. 5B. As shown in FIG. 5A, when multiplexing bitstreams into one bit stream in a unit of block or macro block, there isan effect that the bit stream has a structure that is almost the same asthat of the bit stream obtained by coding the conventional YUV pictures.Further, as shown in FIG. 5B, when multiplexing bit streams into a bitstream in a unit of picture or slice, the unit of inverse multiplexingbecomes greater so that there is an effect that the inverse multiplexingcan be simplified. Further, as the bit stream structure shown in FIG.5C, in the case where information indicating that each of the R, G, andB signals is independently coded is described in the bit stream, thedecoding apparatus can judge easily about whether or not the decodingapparatus can decode the RGB signals independently by checking theinformation when the decoding apparatus decodes the bit stream.

As an example of the variable length decoding method used by thevariable length decoding unit 1001, there is a context adaptivearithmetic decoding method. The context adaptive arithmetic decodingmethod is a method for switching probability tables used for arithmeticdecoding, according to data to be variable length decoded and data thathas been variable length decoded (context adaptation). For example, as acontext for variable-length decoding the quantized frequency transformcoefficients QT, block size for intra prediction, block size forfrequency transformation and the like are used. Here, it is assumed thatthe probability tables are held in the probability table holding unit1010. Also, the probability tables are different for each of R signal, Gsignal and B signal.

Among the quantized frequency transform coefficients obtained byperforming variable length decoding on the bit stream ST and the datafor intra prediction mode and the like, the data of signal DT_R, thedata of signal DT_G and the data of signal DT_B are respectivelyinputted to the decoding units 1002, 1003 and 1004.

FIG. 15 shows a structure of each of the decoding units 1002, 1003, and1004. Hereafter, the operation of the decoding unit 1002 which decodesthe data of R signal DT_R is described. The structure and the operationare the same for the decoding unit 1003 which decodes the data of Gsignal DT_G and for the decoding unit 1004 which decodes the data of Bsignal DT_B.

As shown in FIG. 15, the decoding unit 1002 includes an inversequantization unit 1101, an inverse frequency transform unit 1102, anadding unit 1103, a frame memory 1104, and an inter prediction unit1105.

The decoding unit 1102 decodes each picture of the data of R signal DT_Ras an intra-picture prediction coded picture.

Among the data DT_R, the information indicating the intra predictionmode is inputted to the intra prediction unit 1105 and the quantizedfrequency transform coefficients QT are inputted to the inversequantization unit 1101.

The intra prediction unit 1105 obtains intra reference pixels from theframe memory 1104 and generates an intra predictive image based on theinputted intra prediction mode, and outputs the intra predictive imageto the adding unit 1103.

The quantized frequency transform coefficients QT are inverse quantizedby the inverse quantization unit 1101, are further inverse frequencytransformed by the inverse frequency transform unit 1102, and becomes adecoded differential image LDD. The decoded differential image LDD isadded to the intra predictive image IP by the adding unit 1103 so as toobtain the decoded image LD, and LD is stored in the frame memory 1104.The decoded image stored in the frame memory 1104 is used as a referencepicture in a later decoding. Also, it is outputted as an output pictureOT_R at an appropriate timing.

The output picture of R signal outputted from the decoding unit 1002OT_R, the output picture of G signal outputted from the decoding unit1003 OT_G, and the output picture of B signal outputted from thedecoding unit 1004 are inputted to the signal multiplexing unit 1005,and are outputted as an RGB color picture signal OUT.

As described in the above, the moving picture decoding apparatusaccording to the present invention receives the bit stream obtained bycoding the moving picture of RGB 4:4:4 format as an input bit stream,separates the input bit stream into data of R signal, data of G signaland data of B signal after performing variable length decoding of theinput bit stream, and performs intra predictive decoding respectively onthe data of each signal using respective decoding units. Herein, in theintra prediction for decoding each signal, the intra prediction isperformed using information of the intra prediction mode determinedrespectively for each signal. Further, in the variable length decodingusing arithmetic decoding, the probability tables are held forrespective signals.

Through such operation, the decoding processing after variable lengthdecoding can be performed completely independently for each signal(because it is unnecessary to mutually transfer data and informationamong decoding units) and the structure of the decoding apparatus can besimplified without reducing the coding efficiency. In this case, each ofthe RGB signals has an equal number of pixels so that the decoding unitof each signal can have the same hardware structure.

It should be noted that, while the present embodiment describes the casewhere the picture of RGB 4:4:4 format, that is, a bit stream into whicha picture having three color elements is coded is handled, the decodingprocess can be realized in the same structure even in the case where thenumber of elements is other than the values indicating three colors(e.g. four colors, six colors and the like). With this, the same effectobtained in the present embodiment can be obtained.

(First variation)

The third embodiment can be modified as follows. In the presentvariation, a moving picture decoding apparatus corresponding to themoving picture coding apparatuses in FIGS. 6, 7, and 10 described in thefirst embodiment is to be described.

FIG. 16 illustrates an example of a structure that is different from thedecoding unit 1002 (decoding unit 1003 or 1004) (for the purpose ofdistinction, they are called decoding units 1002 a, 1003 a, and 1004 a).The decoding unit 1002 a includes, in addition to the structure of thedecoding unit 1002 shown in FIG. 15, a motion compensation unit 1206, acontrol unit 1207, and switches 1208 and 1209.

When coding information is multiplexed in the bit stream ST generated bythe moving picture coding apparatuses illustrated in FIGS. 6, 7, and 10,the variable length decoding unit 1001 extracts the coding informationfrom the bit stream ST. This coding information includes the number ofprediction modes and one or more of identifiers of the prediction modesas described in FIGS. 13A to 13D, and further includes assignmentinformation indicating component pictures to which a common predictionmode is assigned when the prediction mode common to the color componentpictures exists in the coding information. According to the predictionmode or the prediction modes indicated by this coding information, thethree decoding units 1002 a, 1003 a, and 1004 a decode respective R, G,and B component pictures.

Whereas the decoding unit 1002 decodes each picture of the data of Rsignal DT_R into an intra-picture predictive coded picture, the decodingunit 1002 a differs from the decoding unit 1002 in that it can decodethe picture of the data of R signal DT_R into an intra-pictureprediction coded picture.

The method for the coding unit 102 a to decode a picture into anintra-picture prediction coded picture is the same as the methoddescribed in the second embodiment. Therefore, the explanation about thesame method is omitted here (the processing is performed by connectingthe switches 1208 and 1209 to “a”).

An operation in the case where the picture of the data DT_R is decodedinto an inter-picture prediction coded picture is to be described. Notethat, herein in the case where the context adaptive arithmetic decodingmethod is used in the variable length decoding unit 1001, differentprobability tables are used for R signal, G signal and B signal.

Among the data DT_R, the coding mode MD is inputted to the control unit1207, the information indicating the intra prediction mode IPM or themotion vector MV is inputted to the switch 1208, and the quantizedfrequency transform coefficients QT are inputted to the inversequantization unit 1101.

The control unit 1207 controls the switch 1208 based on the coding modeMD. In the case where the coding mode MD indicates the intra predictioncoding, the switch 1208 is connected to “a”, and the informationindicating the intra prediction mode IPM is inputted to the intraprediction unit 1105. In the case where the coding mode MD indicates theinter-picture prediction coding, the switch 1208 is connected to “b”,and the motion vector MV is inputted to the motion compensation unit1206. The processing in the case where the coding mode MD indicates theintra prediction coding is the same as the processing explained in thesecond embodiment. Therefore, the explanation about the same processingis omitted here. Hereafter, the case where the coding mode MD indicatesthe inter-picture prediction coding is to be described.

The motion compensation unit 1206, based on the inputted motion vectorMV, obtains reference pixels from the frame memory 1104, generates apredictive picture, and outputs the predictive picture to the addingunit 1103.

The processing of the inverse quantization unit 1101, inverse frequencytransform unit 1102 and adding unit 1103 are the same as the processingexplained in the second embodiment, and the decoded images LDs aregenerated through the processing. The decoded images LDs are stored inthe frame memory 1104. The decoded images stored in the frame memory1104 are used as reference pictures for the later decoding. Also, thedecoded images are outputted as output pictures OT_R at an appropriatetiming.

The output picture of R signal outputted from the decoding unit 1002OT_R, the output picture of G signal outputted from the decoding unit1003, and the output picture of B signal outputted from the decodingunit 1004 OT_B are inputted to the signal multiplexing unit 1005,multiplexed and outputted as an RGB color picture signal OUT.

As described in the above, the moving picture decoding apparatusaccording to the present invention receives a bit stream obtained bycoding the moving picture of RGB 4:4:4 format as an input bit stream,separates the input bit stream into data of R signal, data of G signaland data of B signal after performing variable length decoding of theinput bit stream, and decodes data of each signal independently using adecoding unit that is different for each signal. Herein, in the intraprediction for decoding each signal, the intra prediction is executedusing information of the intra prediction mode determined independentlyfor each signal. Also, in the inter-picture prediction for decoding eachsignal, the inter-picture prediction (motion compensation) is executedusing information of the motion vector determined independently for eachsignal. Further, in the variable length decoding using arithmeticdecoding, each signal respectively holds a probability table.

Through such operation, decoding processing after the variable lengthdecoding can be performed independently for each signal (because it isunnecessary to mutually transfer data and information among decodingunits). Therefore, as a moving picture having a degree of resolutionthat is equal to or greater than the HDTV, in the case where singledecoding apparatus cannot decode a picture because there are too manynumber of pixels to be processed, each signal can be decoded inparallel. In this case, the RGB signals have the same number of pixelsso that a decoding unit of each signal can have the same hardwarestructure. Therefore, even in the case where there are too many numberof pixels to be processed, the structure of the decoding apparatus as awhole and the processing details can be simplified.

Note that it is described that the aforementioned coding informationincludes the number of prediction modes and one or more identifiers ofthe prediction modes, a predetermined prediction mode flag may beincluded instead of the number of prediction modes. Here, the predictionmode flag indicates a flag using one of (1) to (3). There are pluralmethods for representing prediction mode flags.

The first method for representing a prediction mode flag indicates oneof (1) and (3). For example, the flag shown in FIG. 13E indicates thatthe value of the flag is 0 in the case of (1), and 1 in the case of (3).In this case, the structure of a coding stream becomes similar to FIGS.13A, 13B, and 13D.

The second method for representing a prediction mode flag indicates oneof (1) to (3). For example, the flag shown in FIG. 13F indicates thatthe value of the flag is 0 in the case of (1), 1 in the case of (2), and2 in the case of (3). In this case, the structure of a coding streambecomes similar to FIGS. 13A, 13B, 13C and 13D.

The third method for representing a prediction mode flag indicates twosteps (two flags). For example, as shown in FIG. 13G, the firstprediction mode flag indicates (2) or other methods (in other words, (1)or (3)), and when the first prediction mode flag is other than (2),further, the second prediction mode flag indicates either (1) or (3).

With such a prediction mode flag, the picture decoding apparatus caneasily judge whether coding processing has been performed using theprediction mode in one of the above (1) to (3). Furthermore, accordingto the coding information, the prediction modes used in each of thethree decoding units can be identified easily.

Furthermore, in the aforementioned case, a prediction mode flag isdescribed when the number of component pictures for each color is 3.Next, a case where the number of component pictures is generalized intoN is to be described.

In the first method, the prediction mode flag Flag_a indicates one of:(1) that each of the N color component pictures has been coded in anindependent prediction mode; and (3) that the N color component pictureshave been coded in a common prediction mode.

In the second method, the prediction mode flag Flag_b indicates one of:(1) that each of the N color component pictures has been coded in anindependent prediction mode; (3) that the N color component pictureshave been coded in a common prediction mode; and (2) that two or more ofthe N color component pictures have been coded in a common predictionmode and one or more of the N color component pictures other than thetwo or more of the N color component pictures has been coded in anindependent prediction mode.

In the third method, the prediction mode flag includes the first flagflag_c1. The first flag flag_c1 indicates one of: (2) that two or moreof the N color component pictures have been coded in a common predictionmode and one or more of the N color component pictures other than thetwo or more of the N color component pictures has been coded in anindependent prediction mode; and a case other than (2). When the firstflag flag_c1 indicates a case other than (2), the prediction mode flagfurther includes the second flag. The second flag indicates one of: (1)that each of the N color component pictures has been coded in anindependent prediction mode; and (3) that the N color component pictureshave been coded in a common prediction mode.

(Second variation)

The second variation of the third embodiment is described.

A bit stream ST is inputted to the variable length decoding unit 1001.The bit stream ST is obtained by coding the moving picture signal of RGB4:4:4 format, and generated by the moving picture coding apparatusdescribed in the second variation of the first embodiment.

The bit stream ST inputted to the variable length decoding unit 1001 isvariable-length decoded. FIG. 5E shows an example of a bit streamstructure for this case. The second variation differs from the firstvariation of the third embodiment in that the motion vector informationis described commonly for the R signal, the G signal and the B signal inthe macro block that is inter-picture prediction coded. The variablelength decoding unit 1001 copies the motion vector information obtainedby performing variable length decoding on the bit stream ST to the dataof R signal DT_R, the data of G signal DT_G and the data of B signalDT_B, and outputs the result to the decoding units 1002 a, 1003 a and1004 a.

Note that herein in the case where the variable length decoding unit1001 uses the context adaptive arithmetic decoding method, theprobability table for the motion vector is used commonly for the Rsignal, the G signal and the B signal (common among blocks and macroblocks).

The later processing is the same as the processing described in thefirst variation of the third embodiment. Therefore, the explanationabout the same processing is omitted in here.

As described in the above, the moving picture decoding apparatusaccording to the present invention receives the bit stream obtained bycoding the moving picture of the RGB 4:4:4 format as an input bitstream, separates the input bit stream into the data of R signal, thedata of G signal and the data of B signal after variable lengthdecoding, and decodes data of each signal independently using adifferent decoding unit. Herein, in the intra-picture prediction fordecoding each signal, the intra prediction is performed usinginformation of the intra prediction mode determined independently foreach signal. Further, in the inter-picture prediction for decoding eachsignal, the inter-picture prediction (motion compensation) is performedusing information of the motion vector that is common to all of thesignals. Furthermore, in the variable length decoding using thearithmetic decoding, the data other than the motion vector is held in aprobability table for each of the signals.

Through such operation, in the intra-picture prediction coded macroblock within the intra-picture prediction coded picture or within theinter-picture prediction coded picture, decoding is performed completelyindependently for each signal, while in the inter-picture predictioncoded macro block, the motion vector common to all signals is used. Ingeneral, in the intra-picture prediction coded macro block, while theamount of codes for the quantization frequency transform coefficientsoccupies a considerable amount of codes to be generated, the amount ofinformation of the intra prediction mode is small. Further, in theinter-picture prediction coded macro block, the amount of codes for themotion vector has the high percentage of the total amount of codes to begenerated. Therefore, in the processing of the present intra-picturecoded picture, the structure (processing) of the decoding apparatus canbe simplified without reducing the coding efficiency, and in theprocessing of inter-picture prediction coded picture, although thestructure (processing) of the decoding apparatus becomes slightlycomplicated, the coding efficiency can be increased (because the numberof motion vectors described in the bit stream becomes less). Therefore,as a moving picture having a degree of resolution that is equal to orgreater than the HDTV, in the case where a single decoding apparatuscannot decode a picture because there are too many number of pixels tobe processed, each signal can be decoded in parallel. In this case, theRGB signals have the same number of pixels so that a decoding unit ofeach signal can have the same hardware structure.

Note that the present invention is not limited to the aforementionedembodiments, and it is possible to modify or change the presentinvention without departing from the scope of the invention.

Finally, an application example of the moving picture coding apparatusdescribed in the first and second embodiments is to be described.

FIG. 17 is a block diagram illustrating main units of a video camerathat applies the present invention. A video camera 700 is referred to asa three imaging camera, and it differs from the apparatus illustrated inFIG. 10 in that it includes a lens 701, an optical device 702, andimaging devices 703 to 705, instead of the signal separation unit 101.The optical device 702 separates incident light that passes through thelens 701 into primary colors, blue, green and red. The imaging devices703 to 705 capture respective R, G, and B component pictures having thesame number of pixels which correspond to the obtained colors, blue,green and red. The captured three component pictures are inputted to thecoding units 102 c, 103 c, and 104 c.

Note that in FIG. 17, the apparatus may include the coding units 102 b,103 b, and 104 b; the coding units 102 a, 103 a, and 104 a; or thecoding units 102, 103, and 104, instead of the coding units 102 c, 103c, and 104 c.

INDUSTRIAL APPLICABILITY

The present invention is for a moving picture coding apparatus, a movingpicture decoding apparatus, and stream data, and in particular, isapplicable to a moving picture recording/reproducing apparatus, a videocamera, a television camera for professional-use, and the like.

The invention claimed is:
 1. A moving picture coding apparatuscomprising: an obtainment unit operable to obtain N color componentpictures that compose one picture, where N is an integer that is 2 orgreater; N coding units, each of which is operable to code, in one ofintra-picture prediction coding and inter-picture prediction coding, acorresponding one of the N color component pictures, said N coding unitsbeing provided so as to correspond to the N color component pictures;and a signal multiplexing unit operable to multiplex N bit streamsoutputted from said N coding units into one bit stream signal, and tooutput the bit stream signal, wherein said N coding units are operableto individually use respective prediction modes or commonly use aprediction mode for the intra-picture prediction coding or theinter-picture prediction coding, said signal multiplexing unit isoperable to insert, in the bit stream signal, a prediction mode flagindicating correspondence between the N color component pictures andprediction modes to be used for one of the intra-picture predictioncoding and the interpicture prediction coding, the prediction mode flagincludes information indicating whether or not the N color componentpictures have been coded independently, and the prediction mode flagindicates one of: (i) that each of the N color component pictures hasbeen coded in an independent prediction mode; and (ii) that the N colorcomponent pictures have been coded in a common prediction mode.
 2. Amoving picture decoding apparatus comprising: a separation unit operableto separate a bit stream signal into N bit streams corresponding to Ncolor component pictures that compose one picture, where N is an integerthat is 2 or greater, the bit stream signal indicating a coded movingpicture; N decoding units, each of which is operable to decode, in oneof intra-picture prediction decoding and inter-picture predictiondecoding, a corresponding one of the N bit streams, said N decodingunits being provided so as to correspond to the N bit streams; and apicture multiplexing unit operable to multiplex the N color componentpictures from said N decoding units into the one picture, wherein saidseparation unit is operable to separate the bit stream signal into aprediction mode flag indicating correspondence between the N colorcomponent pictures and prediction modes to be used for the intra-pictureprediction decoding, each of said N decoding units is operable toperform the intra-picture prediction decoding according to theprediction mode flag, the prediction mode flag includes informationindicating whether or not the N color component pictures have been codedindependently, and the prediction mode flag indicates one of: (i) thateach of the N color component pictures has been coded in an independentprediction mode; and (ii) that the N color component pictures have beencoded in a common prediction mode.
 3. A moving picture coding methodcomprising: obtaining N color component pictures that compose onepicture, where N is an integer that is 2 or greater; coding, in one ofintra-picture prediction coding and inter-picture prediction coding, acorresponding one of the N color component pictures in N coding unitsthat correspond to the N color component pictures; and multiplexing Nbit streams outputted from the N coding units into one bit streamsignal, and outputting the bit stream signal, wherein the N coding unitsare operable to individually use respective prediction modes or commonlyuse a prediction mode for the intra-picture prediction coding or theinter-picture prediction coding, said multiplexing comprises inserting,in the bit stream signal, a prediction mode flag indicatingcorrespondence between the N color component pictures and predictionmodes to be used for one of the intra-picture prediction coding and theinter-picture prediction coding, the prediction mode flag includesinformation indicating whether or not the N color component pictureshave been coded independently, and the prediction mode flag indicatesone of: (i) that each of the N color component pictures has been codedin an independent prediction mode; and (ii) that the N color componentpictures have been coded in a common prediction mode.
 4. A movingpicture decoding method comprising: separating a bit stream signal intoN bit streams corresponding to N color component pictures that composeone picture, where N is an integer that is 2 or greater, the bit streamsignal indicating a coded moving picture; decoding, in one ofintra-picture prediction decoding and inter-picture prediction decoding,a corresponding one of the N bit streams in N decoding units thatcorrespond to the N bit streams; and multiplexing the N color componentpictures from the N decoding units into the one picture, wherein saidseparating comprises separating the bit stream signal into a predictionmode flag indicating correspondence between the N color componentpictures and prediction modes to be used for the intra-pictureprediction decoding, each of the N decoding units is operable to performthe intra-picture prediction decoding according to the prediction modeflag, the prediction mode flag includes information indicating whetheror not the N color component pictures have been coded independently, andthe prediction mode flag indicates one of: (i) that each of the N colorcomponent pictures has been coded in an independent prediction mode; and(ii) that the N color component pictures have been coded in a commonprediction mode.
 5. A stream data that is computer readable, comprisingN bit streams and a prediction mode flag, wherein said N bit streamsrepresent N color component pictures that compose one picture, where Nis an integer that is 2 or greater, the prediction mode flag includesinformation indicating correspondence between the N color componentpictures and prediction modes to be used for one of intra-pictureprediction coding and inter-picture prediction coding, and informationindicating whether or not the N color component pictures have been codedindependently, and the prediction mode flag indicates one of: (i) thateach of the N color component pictures has been coded in an independentprediction mode; and (ii) that the N color component pictures have beencoded in a common prediction mode.